<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <style>
    .left {
      float: left;
      width: 100px;
      height: 200px;
      background: red;
    }
    .right {
      float: right;
      width: 200px;
      height: 200px;
      background: blue;
    }
    .main {
      margin-left: 120px;
      margin-right: 220px;
      height: 200px;
      background: green;
    }
  </style>
</head>
<body>
  <div class="container">
    <div class="left"></div>
    <div class="right"></div>
    <div class="main"></div>
  </div>
</body>
</html>